The present invention relates to systems (seat components in particular) comprising a cover fastened to a support by means of self gripping elements.
More particularly, the invention relates to a system comprising:
a support,
a flexible cover that covers the support and comprises at least two adjacent parts joined to each other by a seam along a join line, forming a seam flap comprising two margins that belong to the two respective cover parts and that are folded over toward the support from said join line, the seam flap extending from said join line to a free edge and said seam flap having a first face and a second face that belong to the two respective margins, said seam passing around the seam flap and enclosing the free edge of said seam flap from the join line,
and, fastened to the support, at least one self gripping element that comprises hook devices that hook into said seam.
Document U.S. Pat. No. 5,236,243 discloses an example of such system.
The seam used in that type of system must in practice comprise several crimped threads if sufficient hooking force is to be obtained. This creates serious problems of implementation (the difficulty of threading it into a sewing machine needle meaning that threading takes two to three times longer than with a conventional thread, the risk of breakage during seaming, etc.).
It is a particular object of the invention to alleviate these problems by providing a system in which a large hooking force can be obtained between the cover and its support without being forced to use several crimped threads in the seam.
To this end, according to the invention, the seam comprises at least a first thread and a second thread joined to the first and second faces, respectively, of the seam flap along said join line, these first and second threads forming loops that alternate between the faces of the seam flap, each loop of the first thread passing through two adjacent loops of the second thread and each loop of the second thread passing through two adjacent loops of the first thread in the vicinity of the free edge of the seam flap in such a way that said loops of the first and second threads form a mesh in which the seam flap is held tightly and without slack, the loops of the first thread being sewn with greater tension than the loops of the second thread in such a way as to force the seam flap to fold over toward its first face, and the loops of the second thread hooking onto the hook devices of the self gripping element.
Owing to the absence of slack between the seam and the seam flap, and to the fact that one entire face of the seam flap is involved in being hooked to the self gripping element of the support, the system according to the invention results in a very considerable hooking force.
In various preferred embodiments of the self gripping element according to the invention, use may if desired be made of any of the following arrangements:
the join line comprises parallel third and fourth threads;
the second thread is a textured multifilament thread, while the other threads of the seam are of a different type;
the second thread has a count of between 80 and 280 Tex,
the seam is of the so called xe2x80x9cfalse safetyxe2x80x9d type, produced on the basis of stitch No. 512 of the ISO 4915 standard;
the system forms a seat part, while the support forms a padding;
each hook device of the self gripping element comprises a stem that rises from the support toward the seam and that ends in an enlarged head forming several lobes separated angularly from each other by recessed areas, the lobes of the enlarged head projecting out toward the support compared with the recessed areas of said head, and each lobe having a convex face directed away from the support;
the hook devices extend in different directions away from the support;
the hook devices are arranged in pairs of adjacent hook devices on the support, the two hook devices of each pair diverging away from each other and from the support;
most of the hook devices extend in two distinct main directions;
the stem of each hook device is more flexible than the head of the said hook device;
most of the heads of the hook devices comprise four lobes each;
the seam flap is between 7 and 10 mm wide.